We propose continued studies in search of new potential anticancer agents with specific emphasis on drugs that interfere with folic acid metabolism. We believe this to be worthwhile in view of the fact that in the broad field of chemotherapy research, about 10 types of cancer are known to respond to drug treatment. A drug of special interest to us is a derivative of 2-amino-4-hydroxyquinatoline, a potent inhibitor of thymidylate synthetase. Studies of such parameters as the relationship between cell cycle and period of drug exposure are projected. Metabolic flow of one-carbon units into nucleic acids, purine and pyrimidine nucleotides, amino acids and protein will be studied in the presence and absence of anticancer agents with cells grown synchronously in tissue culture. A second major objective is the preparation and use of tracers labeled with short-lived positron-emitting isotopes. By a combination of organic chemical procedures and enzymology (with special emphasis on immobilized enzymes) it is hoped to prepare diagnostic compounds that can be useful in whole body scans. Early diagnosis of cancer as well as an evaluation of cancer treatment by use of these labeled compounds is a long-term objective of these investigations.